Honcho's Long Road to Imola Type-S Zero
- Thread starter Honcho
- Start date
Black belts
The idea is that some rich a$$hole laid a suitcase of cash on the table and convinced Acura to bring in a one-off LHD Zero in 1997. So, it would have LHD and US-spec side marker lights. Of course, it would also have the Acura badging, which my car doesn't. It's an evolving concept LOL. I just want people to do a double-take at car shows. I'll be satisfied with that.
Transmission Refresh 1
Time to begin the long-awaited transmission refresh. On the initial menu is the JDM short gear change, replacing bearings, seals, cleaning and inspection. I will also perform the snap-ring repair, as this particular transmission case is in the range, but not yet failed. Given the difficulty and expense of obtaining a new 6-speed transmission from Japan, I made the decision to invest additional money beyond the initial budget to fully refurbish this 5-speed box so that I can run for a long time if necessary. Thus, I will replace the transmission case and also any synchros/hubs that are showing excessive wear.
This transmission is a US market 5-speed, number J4A4-1005888. It has approximately 70,000 miles and allegedly was removed by the owner to upgrade to a 6-speed. Upon initial inspection, it appears to be in good condition. Lots of spider egg sacs all over and cobwebs, which aligns with the owner's statement that this unit sat in a closet for many years. Thankfully no live spiders or other creatures found.
One thing I noticed that there appeared to be an excessive amount of Hondabond at the case mating surfaces- more that I have seen on other 91-92 MT units. Perhaps this unit has been serviced before?
Lots of Hondabond residue at the spring ball sealing bolts.
Let's get to work.
Ready to separate. As mentioned in other threads on this subject, you must first spread the snap ring open to release the countershaft. You will hear an audible thunk when it drops down. Then, you must separate the two cases. In my case, tapping one of the exposed "ears" of the transmission case with a hammer opened enough of a crack to get a screwdriver in there to work the seam open. I took my time and slowly worked my way around the seam, rocking it open with the screwdriver blade and taking care not to mar the soft aluminum. A plastic trim tool would also work fine here. Then, just lift off the transmission case. We were surprised at how clean the internals were, considering that this transmission sat for years.
The filter. Lots of metal flakes. I could try to clean it, but easier to just replace it with a new one.
The neutral switch was contaminated with a lot of Hondabond. Further suggests this unit was opened before. I may just replace this switch, since the cost is low.
Another mystery- the needle bearing on top of the reverse gear idler shaft had Hondabond stuck to the side of it. Perhaps some broke off the case seams and landed here? What is going on here?
The snap ring. Fully intact. With all the excess Hondabond, I have to wonder if a previous owner had Acura (or an independent shop) perform the snap ring fix on this transmission. However, with no records, I can't be sure. So, I must replace the entire transmission case with a new one just to be sure.
Mainshaft thrust shims. I will measure and cross my fingers that these can be re-used after replacing the mainshaft and the bearings. If not, I'll use the thicker one and calculate the thinner one by measuring the thrust clearance.
Stuck here for the moment- the reverse idler shaft just will not come out. I was able to remove the shift arm with no problem. However, there is a spring pin on the bottom of the reverse shaft that sits in a recessed groove on the clutch case. I must rotate the shaft to align the pin with the groove to lift it out. Except, the shaft won't rotate. It will move about 1 degree in either direction. Given that the shaft sits on a spring washer at the bottom, I wonder if I have to press down on the shaft to compress the washer so it will rotate? Or, do I have to pry on the bottom gear to coax it out? I have an SOS out to Kaz to see if he has any thoughts. [MENTION=10201]goldNSX[/MENTION]? [MENTION=35590]Big McLargeHuge[/MENTION]?
Time to begin the long-awaited transmission refresh. On the initial menu is the JDM short gear change, replacing bearings, seals, cleaning and inspection. I will also perform the snap-ring repair, as this particular transmission case is in the range, but not yet failed. Given the difficulty and expense of obtaining a new 6-speed transmission from Japan, I made the decision to invest additional money beyond the initial budget to fully refurbish this 5-speed box so that I can run for a long time if necessary. Thus, I will replace the transmission case and also any synchros/hubs that are showing excessive wear.
This transmission is a US market 5-speed, number J4A4-1005888. It has approximately 70,000 miles and allegedly was removed by the owner to upgrade to a 6-speed. Upon initial inspection, it appears to be in good condition. Lots of spider egg sacs all over and cobwebs, which aligns with the owner's statement that this unit sat in a closet for many years. Thankfully no live spiders or other creatures found.
One thing I noticed that there appeared to be an excessive amount of Hondabond at the case mating surfaces- more that I have seen on other 91-92 MT units. Perhaps this unit has been serviced before?
Lots of Hondabond residue at the spring ball sealing bolts.
Let's get to work.
Ready to separate. As mentioned in other threads on this subject, you must first spread the snap ring open to release the countershaft. You will hear an audible thunk when it drops down. Then, you must separate the two cases. In my case, tapping one of the exposed "ears" of the transmission case with a hammer opened enough of a crack to get a screwdriver in there to work the seam open. I took my time and slowly worked my way around the seam, rocking it open with the screwdriver blade and taking care not to mar the soft aluminum. A plastic trim tool would also work fine here. Then, just lift off the transmission case. We were surprised at how clean the internals were, considering that this transmission sat for years.
The filter. Lots of metal flakes. I could try to clean it, but easier to just replace it with a new one.
The neutral switch was contaminated with a lot of Hondabond. Further suggests this unit was opened before. I may just replace this switch, since the cost is low.
Another mystery- the needle bearing on top of the reverse gear idler shaft had Hondabond stuck to the side of it. Perhaps some broke off the case seams and landed here? What is going on here?
The snap ring. Fully intact. With all the excess Hondabond, I have to wonder if a previous owner had Acura (or an independent shop) perform the snap ring fix on this transmission. However, with no records, I can't be sure. So, I must replace the entire transmission case with a new one just to be sure.
Mainshaft thrust shims. I will measure and cross my fingers that these can be re-used after replacing the mainshaft and the bearings. If not, I'll use the thicker one and calculate the thinner one by measuring the thrust clearance.
Stuck here for the moment- the reverse idler shaft just will not come out. I was able to remove the shift arm with no problem. However, there is a spring pin on the bottom of the reverse shaft that sits in a recessed groove on the clutch case. I must rotate the shaft to align the pin with the groove to lift it out. Except, the shaft won't rotate. It will move about 1 degree in either direction. Given that the shaft sits on a spring washer at the bottom, I wonder if I have to press down on the shaft to compress the washer so it will rotate? Or, do I have to pry on the bottom gear to coax it out? I have an SOS out to Kaz to see if he has any thoughts. [MENTION=10201]goldNSX[/MENTION]? [MENTION=35590]Big McLargeHuge[/MENTION]?
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I hath been summoned :ghost:
From your last pic it looks like you might still have the reverse shift arm bolted in, have you removed it yet? I was able to lift out all 3 shafts at once by using 2 big zip-ties to hold everything together. The spring pins on the fork and reverse gear sit in their grooves yes, but they will always be aligned and thus you should be able to pull everything straight up and out, no need to compress or pry anything. If you don't want to pull all 3 shafts at once, you can have someone (Spencer? ; )) lift the main & countershafts slightly while you pull out the reverse assy just like if you were reassembling it.
It looks like the case has been opened before, the case sealing bolts look like they've been used a few times already which is consistent with having to measure new thrust & preload shims. Everything looks good so far though, one tip I might add is to test if there's any stripped bolts on the cases by testing the front & rear engine mount bolts and others (like for the cable covers) to see if the threads are good. My case had one stripped front mount hole which I only realized after the trans was reinstalled, would have been nice to fix it on the bench. Make sure the sealing bolt threads are really clean too otherwise you might stretch a bolt over-torqueing it like I did, leftover MTF likes to seep into the threads.
From your last pic it looks like you might still have the reverse shift arm bolted in, have you removed it yet? I was able to lift out all 3 shafts at once by using 2 big zip-ties to hold everything together. The spring pins on the fork and reverse gear sit in their grooves yes, but they will always be aligned and thus you should be able to pull everything straight up and out, no need to compress or pry anything. If you don't want to pull all 3 shafts at once, you can have someone (Spencer? ; )) lift the main & countershafts slightly while you pull out the reverse assy just like if you were reassembling it.
It looks like the case has been opened before, the case sealing bolts look like they've been used a few times already which is consistent with having to measure new thrust & preload shims. Everything looks good so far though, one tip I might add is to test if there's any stripped bolts on the cases by testing the front & rear engine mount bolts and others (like for the cable covers) to see if the threads are good. My case had one stripped front mount hole which I only realized after the trans was reinstalled, would have been nice to fix it on the bench. Make sure the sealing bolt threads are really clean too otherwise you might stretch a bolt over-torqueing it like I did, leftover MTF likes to seep into the threads.
Tyler, the last picture is slightly out of sequence, the reverse shift arm and fork have been removed. We tried pulling the main and counter out all at once but it didn't lift very far, what little it did lift it didn't seem like it would offer enough clearance to lift the reverse idler shaft unit out, but we didn't exactly try that.
Ah, in that case there should be nothing holding in the reverse assy but friction. I would try lifting out all 3 shafts at once, just be careful, they're very heavy and cumbersome hence the zip ties. You'll run into the same problem during reassembly, it's possible but difficult to drop in all 3 shafts plus the forks, but possible to drop in the main & counter and then lift them up a bit to allow the reverse shaft to fit.
Naked cases for reference.
Reverse assy just has one spring pin on the bottom. Shouldn't prevent you from pulling the shaft out. The spring washer is only compressed when the cases are bolted together.
Naked cases for reference.
Reverse assy just has one spring pin on the bottom. Shouldn't prevent you from pulling the shaft out. The spring washer is only compressed when the cases are bolted together.
- Joined
- 15 May 2004
- Messages
- 6,898
Very nice to see a DIY rebuild thread. Memories... 
To remove the reverse gear (it comes out as a set with the shift fork) you have to lift the mainshaft by maybe 1''. Just grab the top of the shaft and the fork, not the gear itself. It's doable with two hands but a third one would be helpful esp. while putting it back in. Tricky step!
To remove the reverse gear (it comes out as a set with the shift fork) you have to lift the mainshaft by maybe 1''. Just grab the top of the shaft and the fork, not the gear itself. It's doable with two hands but a third one would be helpful esp. while putting it back in. Tricky step!
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Thanks guys. Kaz also confirmed that the pin is already aligned in the groove so no need to rotate the shaft. Only thing holding it in is friction and weight. I'll try again tonight. Now that I know I'm not going to break/snap any small metal pieces, I'm sure it will come out. I might try Tyler and John's zip-tie trick...
With 5MT, if you struggled at this stage, you are going to have lots of fun when placing the trans case back in place....
You will be dreaming of having like 5 arms that you can control with your brain.....
6MT is much easier....
Kaz
You will be dreaming of having like 5 arms that you can control with your brain.....
6MT is much easier....
Kaz
- Joined
- 15 May 2004
- Messages
- 6,898
Putting the trans back together is far easier than taking it apart, you just have to figure out the trick for getting the shifter arm on the case properly seated. Like I said in my trans rebuild thread, do a few dry runs and once you get it down wipe with acetone one more time, apply Hondabond, and you're golden.
Going to try the zip tie trick tonight. Last night's attempt was thwarted by puppy.
Going to try the zip tie trick tonight. Last night's attempt was thwarted by puppy.
You can always drop it off the back of a pickup truck and see if it separates.
calling vishnu
You can always drop it off the back of a pickup truck and see if it separates.
The puppy??
haha "someday all this will be yours".... "what" ."the curtains"
:smile:
Paint and Body Work 44
Quick dress-up on the headlight brackets. I used some Rustoleum primer on the surface rust and then 2 coats of some Krylon flat black that I had sitting on the shelf. I only painted what you would see if the headlight cover was removed. Mostly for my own peace of mind- I'm crazy.
Quick dress-up on the headlight brackets. I used some Rustoleum primer on the surface rust and then 2 coats of some Krylon flat black that I had sitting on the shelf. I only painted what you would see if the headlight cover was removed. Mostly for my own peace of mind- I'm crazy.
Paint and Body Work 45
The bumpers were completed. The transformation of the front bumper is incredible. I saw the piece in person and the pictures do not do it justice. PPF is a MUST here. Only thing left is to paint the chassis and do one more coat of clear on the deck lid. I hope to have the car back for re-assembly in about 2 weeks.
The bumpers were completed. The transformation of the front bumper is incredible. I saw the piece in person and the pictures do not do it justice. PPF is a MUST here. Only thing left is to paint the chassis and do one more coat of clear on the deck lid. I hope to have the car back for re-assembly in about 2 weeks.
Transmission Refresh 2
Success.
Thank you to all who advised me here. I was able to remove the reverse shaft using the workshop manual method- no zip ties needed. The main/counter needs to be lifted about 1/2". In my case, friction held up the assembly so perhaps I got lucky. Once it's up, the reverse shaft lifts right out. I tried to take a picture of the assembly lifted. You can see the spacing on the bottom of the select arm shafts- they're about 1/2" out of the holes.
The full assembly.
Time to perform the initial inspection of the synchros. 5th gear below. Although the hub teeth look ok, many of the brass ring teeth are almost completely rounded off. I will replace the entire synchro. Also, there appears to be a lot of chipping and wear at the teeth on 5th gear itself. This is a symptom of fast shifting at high rpm/load and/or skip-shifting from 2 or 3 into 5. I'm questioning the Honda design here- even though the capacity is the same, they've used a really small synchro. Although if you think of the trans as a 4-speed with overdrive, it makes more sense. Still- this is a good example of why you should take it easy shifting into 5th. A new mainshaft 5th gear is $100. Not sure if I should replace it...
The brass teeth look ok here, but others on the ring are perfectly round.
1st gear side of the 2nd gear dual synchro. Looks good. This synchro must have been replaced recently.
2nd gear side of the 2nd gear dual synchro. Also in good shape.
No pictures of the 3-4 synchro on the mainshaft (ran out of time) but it is in good shape. Looks like I will order 5th gear synchro/hub and possibly a new mainshaft 5th.
The magnet. Quite a bit of metal shavings. Probably from that 5th gear.
Next it's time to disassemble the shafts and clean them. Then install the JDM short gears. Have to wait for the new trans case and 5th gear from Japan. Hopefully not too long. I might work on the NSX-R differential conversion instead, as I have all the parts. Have to think of a clever way to hold the diff to loosen the fixing bolts, as I don't have the factory tool.
Success.
Thank you to all who advised me here. I was able to remove the reverse shaft using the workshop manual method- no zip ties needed. The main/counter needs to be lifted about 1/2". In my case, friction held up the assembly so perhaps I got lucky. Once it's up, the reverse shaft lifts right out. I tried to take a picture of the assembly lifted. You can see the spacing on the bottom of the select arm shafts- they're about 1/2" out of the holes.
The full assembly.
Time to perform the initial inspection of the synchros. 5th gear below. Although the hub teeth look ok, many of the brass ring teeth are almost completely rounded off. I will replace the entire synchro. Also, there appears to be a lot of chipping and wear at the teeth on 5th gear itself. This is a symptom of fast shifting at high rpm/load and/or skip-shifting from 2 or 3 into 5. I'm questioning the Honda design here- even though the capacity is the same, they've used a really small synchro. Although if you think of the trans as a 4-speed with overdrive, it makes more sense. Still- this is a good example of why you should take it easy shifting into 5th. A new mainshaft 5th gear is $100. Not sure if I should replace it...
The brass teeth look ok here, but others on the ring are perfectly round.
1st gear side of the 2nd gear dual synchro. Looks good. This synchro must have been replaced recently.
2nd gear side of the 2nd gear dual synchro. Also in good shape.
No pictures of the 3-4 synchro on the mainshaft (ran out of time) but it is in good shape. Looks like I will order 5th gear synchro/hub and possibly a new mainshaft 5th.
The magnet. Quite a bit of metal shavings. Probably from that 5th gear.
Next it's time to disassemble the shafts and clean them. Then install the JDM short gears. Have to wait for the new trans case and 5th gear from Japan. Hopefully not too long. I might work on the NSX-R differential conversion instead, as I have all the parts. Have to think of a clever way to hold the diff to loosen the fixing bolts, as I don't have the factory tool.
